Selective hydraulic pressure booster for borehole apparatus



Aug. 30, 1966 u. E. VOETTER 3,269,462

SELECTIVE HYDRAULIC PRESSURE BOOSTER FOR BOREHOLE APPARATUS Filed March L7, 1964 :5 Sheets-Sheet 1 fimlAi mk 0, 1 u. E. VOETTER 3,269,462

SELECTIVE HYDRAULIC PRESSURE BOOSTER FOR BOREHOLE APPARATUS Filed March 7.7, 1964 5 Sheets-Sheet 2 i g V 75 n i I ATTO/P/V J' Aug. 30, 1966 VOETTER 3,269,462

SELECTIVE HYDRAULIC PRESSURE BOOSTER FOR BOREHOLE APPARATUS Filed March .7, 1964 5 Sheetsfiheet 5 U/xvc/x f. l ae/ze/ INVENTOR.

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ATTO/FA/[V United States Patent berger Well Surveying Corporation, Houston, Tex., a

corporation of Texas Filed Mar. 17, 1964, Ser. No. 352,515 6 Claims. (Cl. 166--100) The present invention relates to borehole apparatus and, more particularly to a new and improved hydraulic means which, in response to hydrostatic pressure of a well fluid, develops a hydraulic pressure for actuation of certain wellbore tools, which pressure is greater than this hydrostatic pressure by a preselected one of a number of predetermined ratios.

Certain conventional well-bore tools require that particular members thereof be capable of being selectively moved from a first position to other positions whenever the tool has been positioned for operation within a well bore. Such movable members may be, for example, an extendible arm or a pad member which is normally retracted to allow the well tool to be freely maneuvered within a well bore and then extended outwardly as desired for an operative purpose.

Although various mechanical and electrical devices have been proposed previously to actuate such movable members, one of the most successful arrangements has been a hydraulic system employing the [hydrostatic pressure of the well fluid itself as a motivating source. In such arrangements, the hydraulic system is designed in such a manner that the hydraulic pressure developed is sufiiciently greater than the hydrostatic pressure of the well fluid to enable the movable members to move easily against the opposing hydrostatic force of the well fluid. These hydraulic systems typically include a slidably mounted master piston coupled through a filled hydraulic system to one or more slidably mounted follower 0r actuator pistons. The master piston has an enlarged outer end arranged to be selectively placed in communication with the well fluid and a reduced inner end for displacing the hydraulic fluid to drive the follower pistons. Thus, application of hydrostatic pressure upon the enlarged end of the master piston will depress the master piston and raise the pressure of the hydraulic system to a magnitude equal to the product of the hydrostatic pressure multiplied by the ratio of the cross-sectional area of the enlarged end to that of the reduced end.

It will be appreciated, of course, that with a given master piston, the hydraulic pressure developed will depend solely upon the hydrostatic pressure of the well fluid, and in turn that this hydrostatic pressure depends solely upon the depth at which the well tool happens to be situated. Furthermore, those skilled in the art recognize that although the hydraulic pressure must be increased to at least a certain minimum before reliable operation can be obtained, this hydraulic pressure must still be held within reasonable maximum limits to prevent failure of flow lines, seals and other system components.

Operating problems arise, however, since it is not at all uncommon to encounter oil wells so deep that hydrostatic pressures therein will approach 15,000 to 20,000 p.s.i.g. Thus, by way of illustration, if a master piston having an area ratio of 5:1 were used at such great depths, the developed hydraulic pressure would approach 100,000 p.s.i.g. So, in such deep wells, it is customary to use smaller piston ratios, such as 2:1 for example, so that the hydraulic pressure developed will not exceed 40,000 p.s.i.g. On the other hand, where a well tool is operated in a fairly shallow well with a hydrostatic pressure of only 500 p.s.i.g., the same 2:1 piston would develop a hydraulic pressure of only 1,000 p.s.i.g. which would give 3,269,462 Patented August 30, 19fi6 a useful differential of only 500 p.s.i., which differential is generally insuflicient for reliable actuation of most movable members.

Thus, it has become necessary to provide interchangeable master pistons having different area ratios to accommodate the widely differing hydrostatic pressures encountered in the normal service of a particular well tool. By Way of example only, three different pistons generally provide both safe and reliable operation up to a hydrostatic pressure of approximately 20,000 p.s.i.g. For example, one of these pistons could have a ratio of 6:1 for operation up to 4,000 p.s.i.g.; another could have a ratio of 3:1 for operation from 4,000 to 10,000 p.s.i.g.; and the third piston could have a ratio of 2:1 for operation from 10,000 to 20,000 p.s.i.g. Thus, it will be appreciated that by using such interchangeable pistons, the hydraulic pressures developed will not exceed 40,000 p.s.i.g. and the differential pressures will usually be sufficiently high at even the lower hydrostatic pressures.

It will be appreciated, however, that although interchangeable sets of pistons will enable a single well tool to be operated at all depths, certain problems will still arise. First of all, it is generally impractical to interchange the pistons in the field chiefly because of the amount of time required to make such changes as well as the risk that dirt may get into the hydraulic system. Accordingly, as a practical matter, to secure effective service, it is usually necessary to provide duplicate well tools which differ only in the particular area ratio of their master piston. It will of course be realized that such duplication requires a considerable capital investment which could be otherwise used for other purposes.

Accordingly, it is a general object of the present invention to provide a new and improved master piston which is capable of developing a preselected one of a number of different output pressures by means of a simple adjustment which may be readily made in the field.

It is still another object of the present invention to provide a new and improved hydraulic pressure booster for operation over a wide range of hydrostatic well bore pressures without subjecting the equipment in which it is to be used to excessively high hydraulic pressures.

In general, the apparatus to the present invention consists of a plurality of concentrically arranged pistons so interconnected that diflering ratios of pressure multiplication can be easily and selectively obtained by allowing one or more of these pistons to be active.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a view of an earth formation fluid sampler device in which the present invention may be used, with the fluid sampler device being shown within a well bore prior to actuation of its extendible wall-engaging samplecollecting member;

FIG. 2 is a schematic representation of the major components of the sampler apparatus as illustrated in FIG. 1;

FIGS. 3A and 3B are longitudinal cross-sectional views of a preferred embodiment of the new and improved piston or hydraulic pressure booster of the present invention;

FIG. 4 is a cross-sectional view taken along the line 44 of FIG. 3;

FIG. 5 is a view similar to FIG. 3, but illustrating an alternate operating position; and

FIG. 6 is a view similar to FIG. 3, but illustrating still another operating position.

Although other applications for the present hydraulic booster will be readily apparent to those skilled in the 3 art, a typical application for such a booster would be in apparatus as shown and fully described in Patent No. 3,011,554 to Robert Desbrandes and Roger Q. Fields for Apparatus for Investigating Earth Formations.

As seen in FIG. 1, this apparatus is suspended from a wireline 11 having electrical conductors and positioned in a well bore 12 adjacent a particular earth formation 13 to collect a sample of whatever conate fluids there may be in that formation. The apparatus 10 consists basically of a pair of opposed extendible pad members 14, 15, a hydraulic actuating system having the hydraulic booster of the present invention design, and a fluid-sample collecting system.

By opening an explosively actuated valve, the hydraulic system is actuated to extend the pad members 14, 15 outwardly to firmly press an annular sealing member 16 on pad member 14 into sealing engagement with the exposed face of the formation 13 to be investigated. A specially arranged shaped charge or perforating bullet is then fired through a normally closed sample port Within the central opening of this sealing member to open the port and develop a perforation leading into the formation 13. Since the annular sealing member 16 isolates this central opening from the hydrostatic pressure of the well fluids 17, the natural formation pressure will expel a sample of any conate fluids into the isolated central opening, through this sample port, and on into a sample collecting chamber in the apparatus 10. Then, after a sufficient time has elapsed, a hydraulically actuated valve is closed to seal the sample chamber, the pad members 14, 15 are retracted, and the apparatus 10 is retrieved.

Turning now to FIG. 2, the major components of the apparatus 10 are shown schematically for purposes of illustrating the operation of the apparatus in relation to the pressure booster 18 of the present invention. Inasmuch as the particular details of the basic system and the other components are not necessary for a full understanding of the present invention and are described in great detail in Patent No. 3,011,554, the description of these systems and other components will be limited to only what is necessary for understanding of the basic functions of each of the principal components and their general relation to each other.

In a lower section of apparatus 10 is found the samplereceiving system which includes a sample-receiving vessel 19 having a transverse partition 20 dividing the vessel into upper and lower chambers 21, 22. A floating piston 23 is slidably mounted within upper chamber 21 and arranged to travel downwardly from the position shown in FIG. 2. Before apparatus 10 is lowered into a well, floating piston member 23 is moved to its uppermost position and that portion of upper chamber 21 beneath piston 23 is filled with water. Although it is not essential that the upper chamber 21 be filled with water, this usually is done to protect an unconsolidated formation from the deleterious effects of a sudden expulsion of conate fluids. Lower chamber 22 contains only air at either atmospheric pressure or at some slightly higher pressure.

Thus, it will be appreciated that as the formation pressure expels the conate fluids into upper chamber 21, floating piston member 23 will be displaced downwardly as the formation fluid begins to fill that space above the piston member. The speed of the downward travel of piston member 23 is of course regulated by the speed at which the water 24 contained in upper chamber 21 is expelled out of a restricted opening 25 through the partition 20. Accordingly, whenever a sufficient volume of formation fluids have been captured in that part of upper chamber 21 above floating piston 23, the piston member 23 will engage the partition 20 and come to rest thereon.

Basically, the mechanical portion of the apparatus 10 is comprised of oppositely-mounted normally-retracted pack-off and back-up shoes 14, 15 which are hydraulically driven outwardly into engagement with the wall of the borehole. The back-up shoe 15 keeps the apparatus 10 substantially centered within the borehole 12 as force is being applied by the pack-off shoe 14 against the formation face.

As shown in greater detail in Patent No. 3,011,554, pack-off shoe 14 has an annular sealing member 16 disposed on its outer face to enclose a substantial central area which is isolated from the Well fluids 17 whenever sealing member 16 is sealingly engaged against a formation 13. An entry port 26 provided in this enclosed central area is initially covered with a frangible closure member. A conventional perforating device, such as a bullet or shaped charge 27, is arranged within pack-off shoe 14 in such a manner that when detonated, the closure member will be pierced and the bullet or the jet action of the shaped charge 27 will produce a perforation in the formation 13 opposite to entry port 26.

Turning now to the hydraulic system of the apparatus 10, the greater portion of this hydraulic system is contained in the upper portion of the apparatus housing. The master piston 18 of the present invention is operatively mounted therein with its outer end being initially isolated from the well fluids 17 by an electrical-1y initiated explosively actuated valve 28, such as that shown in FIG. 4 of the Patent No. 3,011,554. It will be appreciate-d from the schematic representation of this valve 28 that when a small explosive charge 29 is detonated, a member 30 is impelled against a frangible sealing plug 31 with such force that sealing plug 31 is broken to open fluid communication from the well fluids to the enlarged upper end 32 of piston member 18. Accordingly, whenever the plug 31 is broken, the hydrostatic pressure of the well fluids 17 acting on the upper end 32 of piston member 18 will drive the piston 18 downwardly to develop a hydraulic pressure in the hydraulic system. This developed hydraulic pressure will, of course, be in direct proportion to the ratio of the areas of the opposite ends 32, 33 of piston member 18. Piston members 34, 35, 36 and 37 are operatively arranged in such a manner as to extend the back-up and pack-off shoes 14, 15 into engagement with the opposite faces of the well bore 12 whenever the hydraulic pressure is sufliciently great.

Although it is not essential, it is usually preferred to include a pressure-regulating valve 38 in the hydraulic system between the master piston 18 and the follower or actuator pistons 3437. This valve 38, as shown in detail in FIGS. 8 and 8-A of Patent No. 3,011,554, is fully responsive to the hydrostatic pressure of the well fluids 17 and is so arranged that a spring-biased ball valve 39 is held fully open and accordingly is ineffective until such time that the differential between the -hydrostatic well pressure and the hydraulic pressure developed by the master piston 18 approaches a predetermined magnitude, which differential is preferably 6,000 to 10,000 psi. As this selected differential is approached, the increasing hydraulic pressure will begin to close the ball valve 39 against the opposition of a spring-biased piston member 40 which is responsive to the hydrostatic pressure of the well fluids 17. Thus, when the hydraulic pressure reaches a particular magnitude, the ball valve 39 will be completely closed to isolate the master or booster piston 18 from the follower pistons 34-37 and maintain whatever hydraulic pressure there is in the system downstream of the ball valve 39. Any additional increase of the developed hydraulic pressure upstream of valve 39 will, of course, merely tend to seat the ball valve more tightly and not affect the downstream hydraulic pressure.

Should the downstream hydraulic pressure drop for any reason, however, the pressure-regulating piston 40 will again urge the ball valve 39 open which allows more hydraulic fluid at the higher developed pressure to bleed through and again raise the downstream pressure. Thus, it will be appreciated that whenever the developed hydraulic pressure reaches a particular magnitude, the pressure downstream of the pressure regulator valve 38 will generally be maintained at a fairly constant differential relative to the hydrostatic pressure of the well fluids in the well bore.

In operation, whenever the apparatus has been positioned adjacent the formation 13 to be tested, the small explosive charge 29 is electrically detonated to open the mud valve 28 and expose the enlarged end 32 of the master piston 18 to the hydrostatic pressure of the well bore fluid 17. This drives the master piston 18 inwardly to develop a hydraulic pressure and drive the actuator pistons 34-37 outwardly to extend the shoes 14, 15 into engagement against opposite walls of the borehole 12. When the pack-off shoe 14. is pressed against the exposed face of the formation 13, the annular sealing member 16 will isolate a portion of that formation face from the drilling mud 17 in the borehole 12. The shaped charge 27 is then detonated to open the entry port 26 and develop a perforation into the formation 13 at this point to allow conate formation fluids to be expelled and forced into the sample-receiving vessel 19 by the natural formation pressure. As the conate fluids enter vessel 19, floating piston 23 is gradually displaced downwardly until it comes to rest on partition 20.

After a desired amount of formation fluid has been obtained, a second electrically initiated explosively actuated valve 41 is opened to divert hydraulic fluid into a second conduit 42 leading to a piston-actuated valve 43 which closes the fluid inlet of the sample-receiving vessel 19. An orifice 44 in a branch conduit 45 leading from conduit 42 retards the discharge of hydraulic fluid into an empty dump chamber 45 at atmospheric pressure so as to allow suflicient time for the hydraulic pressure to close the seal valve 43. Hydrostatic pressure entering through entry port 26 will hold seal valve 43 closed as apparatus 10 is retrieved. In time, however, suflicient hydraulic fluid will have bled through orifice 44 into the dump chamber 46 to substantially reduce the hydraulic pressure in the entire system (pressure-regulator valve 38 will now be open) which enables hydrostatic pressure aided by springs 47, 438 to retract the follower pistons 3437 and pack-off and back-up shoes 14, 15.

Although, further operational procedures may be required to retract the pack-off and back-up shoes, these particular details do not pertain to the present invention and are fully explained in Patent No. 3,011,554.

Turning now to FIG. 3, the master piston 18 of the present invention is shown in detail. The housing 49 for the piston is formed of tandemly arranged housing sections 50, 51 of substantially equal outer diameters with the upper section being connected by threads 52 and fluidly sealed at 53 to the lower housing section 51.

Upper housing section 50 is provided with a continuous axial bore extending completely through the housing section which is formed by a series of concentrically aligned bore portions of varying diameters. This continuous bore is comprised of an enlarged diameter bore 54 which extends from the upper end 55 to near the lower end 56 of the housing section 50, where it converges to form a first annular shoulder 57 and then joins a second bore portion 58 of a slightly reduced diameter. This second bore portion 58 continues only a short distance before converging to form a second annular shoulder 59 and joining a third bore portion 60 of a still smaller diameter. This third bore portion 68 extends only a short distance before diverging to form an oppositely directed annular shoulder 61 and opening into a slightly enlarged diameter fourth bore portion 62, which latter-named bore portion continues uninterrupted to the lower end 56 of the housing section 50.

Lower housing section 51 has an enlarged socket 63 for receiving a reduced outer diameter portion 64 at the lower end 56 of the upper housing section 50. The bottom of this socket 63 converges into a reduced diameter longitudinal bore 65 which has a diameter equal to that of the fourth bore portion 62 in upper housing section 50. Longitudinal bore 65 continues substantially the full length of lower housing section 51 before terminating at a reduced diameter outlet passage 66. Outlet passage 66 may be arranged to receive any conventional fluidly sealed connector for connection to a hydraulic system such as that described above.

The upper end 55 of upper housing section 50 may be closed with any conventional closure member, such as a shouldered end plug 67 which is inserted into and sealingly received by the open upper end of enlarged bore portion 54. An inlet passage 68 through end plug 67 provides fluid communication to the explosively actuated mud valve 28 previously described.

An elongated tubular member 69 is slidably mounted along the central axis of housing 49 and arranged for limited travel therein with fluid seals 711! being provided to fluidly seal this member relative to the housing where it passes through the third bore portion 60. The lower end of tubular member 69 is provided with an annular guide 71 to maintain the axial alignment of the tubular member as well as to limit its upward travel by engaging the downwardly directed annular shoulder 61 at the junction of the third bore portion 60 and the enlarged fourth bore portion 62. An enlarged head 72 provided at the upper end of tubular member 69 serves to limit downward travel of the member by engaging the upwardly facing second annular shoulder 59 at the junction of the second 58 and third 60 bore portions.

A second elongated tubular member 73 is slidably received within the bore 74 of tubular member 69 and extended from both ends thereof. Annular sealing members 75 disposed around the bore 74 of the outer member adjacent its enlarged head 72 fluidly seal the members relative to one another. The lower end of the inner member 73 extending below outer tubular member 69 is provided with an annular guide member 76 which limits upward travel of the inner member whenever that guide 76 engages the lower guide 71 of the outer tubular member 69. An enlarged head 77, similar to head 72, provided on the upper end of the inner member 73 serves to limit the downward travel of the inner member whenever its enlarged head 77 engages the enlarged head 72 of the outer member. Annular sealing rings 78 are mounted around the bore 79 of the inner member adjacent its enlarged head 77.

An elongated cylindrical plunger member 80 of a uniform diameter is slidably mounted for axial travel within the bore 79 of inner tubular member 73 and is fluidly sealed relative to that member by sealing rings 78. Although a rigid interconnection could be used with success, it is preferred to employ a separate piston member 81 to depress plunger 80. Accordingly, a floating piston 81 having annular sealing rings therearound and a crosshead 82 are slidably mounted in enlarged bore portion 54 with the crosshead 82v being below the mud piston Y81 and suitably connected to the upper end of plunger 80. Thus, it will be appreciated that should the enlarged bore portion 54 be slightly misaligned relative to the telescoping tubular members 69, 76, the plunger will still be able to travel freely without being bound. Other advantages of this arrangement will be subsequently explained.

It will be appreciated that telescoping members 69 and 73 are free to travel a limited amount not only relative to one another but also with respect to housing 49. Ac cordingly, as part of the present invention, a series of individual locking members are strategically arranged to permit an operator to quickly and easily make adjustments which in effect allows him to select any one of three possible hydaulic output pressures that will be developed.

Briefly, the locking members employed in the present invention are elongated members which are easily deflected along their longitudinal axes but. have sufficient strength to withstand substantial laterally directed forces tending to shear or collapse the members along their transverse axes. Accordingly, it has been found that appropriately designed coil springs of a relatively small diameter with suflicient length to substantially encircle the slidable member to be locked will meet these requirements. Accordingly, complementary annular grooves are appropriately formed in the various members in such a manner that when one groove is aligned with its counterpart, such a spring may be inserted therein to prevent relative travel of those members. It will be understood, of course, that these holding members may have other configurations.

Thus, to fix the outer tubular member 69 relative to housing 49, an annular groove having a semi-circular cross-section is cut in the housing around the wall of the second reduced bore portion 58 with a corresponding annular groove being cut around the periphery of enlarged head 72 of the outer tubular member. Thus, when these mating grooves are juxtaposed, an annular recess of circular cross-secton is formed into which a complementary elongated coil spring 83 may be inserted.

A similar arrangement of mating semi-circular annular grooves allows the inner tubular member 73 to be fixed relative to housing 49 by inserting a second spring 84 into the recess formed around enlarged head portion 77 of that tubular member. Furthermore, for fixing inner tubular member 7 3 relative to outer tubular member 69, a similar arrangement of matched annular grooves is provided around the bore 74 of the outer member 69 and around the periphery of the inner member 73 at a common point substantially near the upper ends of the members, which recess will receive a third spring member 85.

A fourth set of such annular grooves is provided for locking the plunger 80 relative to inner member 73. One 86 of these semi-circular grooves is formed around plunger 80 near its upper end and the mating groove 87 is formed around the bore 89 of inner member 73 near its upper end.

Access to these mating grooves is easily had through normally closed access ports 88, 89 in the outside of the housing 49. As seen in FIG. 4, access port 88, normally closed by a closure member 90, extends through the housing adjacent the annular grooves provided for receiving springs 84, 91 for respectively locking the inner tubular member 73 to the housing 49 and to the plunger member 80. Openings 92, 93 (FIG. 4) through enlarged head portion 77 allow spring 91 to be inserted through the access port 88 for locking the plunger 80 to the inner tubular member 73. Access port 89 provides access in the same manner to springs 83 and 85 which lock outer tubular member 69 to the housing 49 and inner tubular member 73, respectively. It is to be understood that, although not shown, openings similar to 92 and 93 are provided through enlarged head 72 to allow insertion and removal of spring 85.

Accordingly, it will be appreciated that by correctly arranging springs 83, 84, 85 and 91, any one of three operative arrangements may be selected. As seen in FIG. 3, both of the telescoping tubular members 69, 73 are held fixed relative to each other and to housing 49. Thus, with this arrangement, only plunger 80 is free to travel. The travel of plunger 80 will be limited only by the distance below crosshead 82 to the top of enlarged head 77. Hy draulic fluid beneath the plunger will be substantially confined in lower housing section 51, with sealing rings 78 serving as the seal through which the plunger travels and sealing rings 70 and 75 preventing leakage between the telescoped members and between the housing and the outer member. It will also be appreciated that with the tubular members 69 and 73 being held fixed, the ratio of the respective cross-sectional areas of the mud piston 81 to the plunger 80 is substantial. Thus, the hydraulic pressure developed will be equal to the hydrostatic pressure multiplied by this ratio.

In FIG. 5, a second alternative operative arrangement is illustrated in which the inner tubular member 73 has been freed by removing springs 83 and 85 and operatively connected to plunger 80 by spring 91. Thus, the effective pressure multiplication ratio has been reduced somewhat by the addition of the cross-sectional area of tubular member 73 to that of the plunger 80. It should also be realized that the span of travel of the combined plunger 80 and inner tubular member 73 is restricted to the distance between annular guides 71 and 76. It is generally desirable to maintain the total displacement volume fairly uniform; so, by proper proportions, the length of travel of the combined members may be reduced appropriately as the effective plunger area is increased to maintain the total displaced volume constant. In this arrangement, seal members 75 serve as the seal through which the combined plunger and sleeve 73 travel, with seals 70 preventing leakage around the outer tubular member 69 and seals 78 preventing leakage around the plunger itself.

In FIG. 6, the outer sleeve or tubular member 69 has been freed from the housing 49 and operatively connected by spring to the combined plunger 80 and inner sleeve 73. In this instance, the span of plunger travel has again been reduced, with the travel being limited to the distance between annular guide 71 and downwardly facing shoulder 61. Also, the combined cross-sectional area will further reduce the pressure multiplication ratio to still a third value.

It will be appreciated that whenever the piston 18 is operated and well fluids enter the enlarged bore 54 above mud piston 81, these corrosive fluids should be expelled whenever the apparatus 10 is retrieved. This can be easily accomplished with the present invention by introducing compressed air into one of the access ports 88 or 89 which forces the mud piston 81 to its uppermost position and displaces the Well fluids confined above the piston out through inlet passage 68. It will be readily understood that if mud piston 81 were coupled to plunger 80, the piston 81 could not be so returned unless one or more of the latching springs 83, 84, 85 or 91 were first removed. Thus, by leaving piston 81 free as shown, the enlarged bore 54 may always be flushed out easily without removing the latching springs.

Accordingly, it will be understood that the operator of a well tool employing the present invention will now have the capability to quickly select the operative arrangement that will allow the equipment to be operated within a pressure range that will give positive actuation of the hydraulically actuated members without the hydraulic pressures becoming excessively high. Furthermore, it should be noted that all of these adjustments can be performed in the field without risking contamination or requiring draining of the hydraulic fluid in lower housing section 51 since both access ports 88 and 89 are above seals 70 and 75.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. In a well tool adapted for use in a fluid-filled well bore, a housing having a cylindrical bore therein; a movable member operatively mounted on said housing and arranged for movement between at least two positions; and hydraulic'means responsive to hydrostatic pressure of a well fluid for moving said movable member from one of said positions to another, said hydraulic means including: a piston member disposed in said bore and arranged for movement from a first position to a second position, said piston having an enlarged portion at one end and a reduced portion at the opposite end thereof; a tubular sleeve 9 member slidably mounted on said reduced portion; means providing a fluid seal of said enlarged portion relative to said housing; means providing a fluid seal of said reduced portion relative to said sleeve member; means providing a fluid seal of said sleeve member relative to said housing; means for selectively placing the exterior of said housing in fluid communication with said enlarged portion for imposing hydrostatic pressure of well fluids onto said enlarged portion to move said piston from said first position to said second position; and means for selectively holding said sleeve member fixed relative to either of said housing or to said piston member.

2. In a well tool adapted for use in a fluid-filled well bore, a housing having a cylindrical bore therein; a movable member operatively mounted on said housing and ar ranged for movement between at least two positions; and hydraulic means responsive to hydrostatic pressure of a well fluid for moving said movable member from one of said positions to another, said hydraulic means including: a piston member disposed in said bore and arranged for movement from a first position to a second position, said piston having an enlarged portion at one end and a reduced portion at the opposite end thereof; a first tubular sleeve member slidably mounted on said reduced portion; a second tubular sleeve member slidably mounted on said first sleeve member; means providing a fluid seal of said enlarged portion relative to said housing; means providing a fluid seal of said reduced portion relative to said first sleeve member; means providing a fluid seal of said first sleeve member relative to said second sleeve member; means providing a fluid seal of said second sleeve member relative to said housing; means for selectively placing the exterior of said housing in fluid communication with said enlarged portion for imposing hydrostatic pressure of well fluids onto said enlarged portion to move said piston from said first position to said second position; means for selectively holding said first sleeve member fixed relative to either said housing or to said piston member; and means for selectively holding said second sleeve member fixed relative to either said housing or to said piston member.

3. In a well tool adapted for use in a fluid-filled well bore, a housing having a cylindrical bore therein; a movable member operatively mounted on said housing and arranged for movement between at least two positions; and hydraulic means responsive to hydrostatic pressure of a well fluid for moving said movable member from one of said positions to another, said hydraulic means including: a plunger member disposed in said bore and arranged for movement from a first position to a second position; a piston member sealingly received in said bore adjacent one end of said plunger member and arranged for movement between at least two positions, said piston member being adapted to engage said one plunger end to urge said plunger to its second position; a tubular sleeve member sealingly engaged with and slidably mounted around said plunger member; means providing a fluid seal of said sleeve member relative to said housing; means for selectively placing the exterior of said housing in fluid communication with said piston member for imposing hydrostatic pressure of well fluids onto said piston member for moving it into engagement with said one plunger end to urge said plunger to its second position; and means for selectively holding said sleeve member fixed relative to either said housing or to said plunger member.

4. In a well tool adapted for use in a fluid-filled well bore, a housing having a cylindrical bore therein; a movable member operatively mounted on said housing and ariii ranged for movement between at least two positions; and hydraulic means responsive to hydrostatic pressure of a well fluid for moving said movable member from one of said positions to another, said hydraulic means including: a plunger member disposed in said bore and arranged for movement from a first position to a second position; a piston member sealingly received in said bore adjacent one end of said plunger member and arranged for movement between at least two positions, said piston member being adapted to engage said one plunger end to urge said plunger to its second position; a first tubular sleeve member sealingly engaged with and slidably mounted around said plunger member; a second tubular sleeve member sealing- 1y engaged with and slidably mounted around said first sleeve member; means providing a fluid seal of said second sleeve member relative to said housing; means for selectively placing the exterior of said housing in fluid communication with said piston member for imposing hydrostatic pressure of well fluids into said piston member for moving it into engagement with said one plunger end to urge said plunger to its second position; and means for selectively holding said first sleeve member fixed relative to either said housing or to said plunger member; and means for selectively holding said second sleeve member fixed relative to either said housing or to said plunger member.

5. The apparatus of claim 4 in which: said plunger member and said first tubular sleeve member have annular grooves in their respective mating surfaces, said grooves forming a first annular recess whenever said grooves are juxtaposed; said first tubular sleeve member and said second tubular sleeve member have annular grooves in their respective mating surfaces, said grooves forming a second annular recess whenever said grooves are juxtaposed; said second tubular sleeve member and said housing have annular grooves in their respective mating surfaces, said grooves forming a third annular recess whenever said grooves are juxtaposed; and said first and second selective holding means including at least one elongated deflectable member sized and adapted for reception into any one of said annular recesses.

6. In a well tool for use in well bore, said tool having hydraulically operated means; a hydraulic actuating system for applying hydraulic pressure to said hydraulically operated means; said system including: a housing having a cylinder forming a bore, said cylinder having fluid inlet and outlet means; piston means slidably and sealingly re ceived in said bore intermediate of said inlet and outlet means; said inlet means serving to admit fluid under pressure to one side of said piston means; said outlet means serving to discharge fluid from said cylinder to said hydraulically operated means; said piston means and cylinder having portions of different effective cross-sectional area sized for creating a pressure differential between said inlet and outlet means; and means for selectively changing the effective cross-sectional area of said portions between said cylinder and piston means.

References Cited by the Examiner UNITED STATES PATENTS 239,127 3/1881 Wellman 92-6 676,251 6/1901 Hagman 926 X 3,011,554 12/1961 Desbrandes et al. 166-100 3,106,320 10/1963 Campbell et a1. 103-37 CHARLES E. OCONNELL, Primary Examiner.

D. H. BROWN, Assistant Examiner. 

6. IN A WELL TOOL FOR USE IN WELL BORE, SAID TOOL HAVING HYDRAULICALLY OPERATED MEANS; A HYDRAULIC ACTUATING SYSTEM FOR APPLYING HYDRAULIC PRESSURE TO SAID HYDRAULICALLY OPERATED MEANS; SAID SYSTEM INCLUDING: A HOUSING HAVING A CYLINDER FORMING A BORE, SAID CYLINDER HAVING FLUID INLET AND OUTLET MEANS; PISTON MEANS SLIDABLY AND SEALINGLY RECEIVED IN SAID BORE INTERMEDIATE OF SAID INLET AND OUTLET MEANS; SAID INLET MEANS SERVING TO ADMIT FLUID UNDER PRESSURE TO ONE SIDE OF SAID PISTON MEANS; SAID OUTLET MEANS SERVING TO DISCHARGE FLUID FROM SAID CYLINDER TO SAID HYDRUALICALLY OPERATED MEANS; SAID PISTON MEANS AND CYLINDER HAVING PORTIONS OF DIFFERENT EFFECTIVE CROSS-SECTIONAL AREA SIZED FOR CREATING A PRESSURE DIFFERENTIAL BETWEEN SAID INLET AND OUTLET MEANS; AND MEANS FOR SELECTIVELY CHANGING THE 